State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, P.R. China.
Sci Rep. 2019 May 14;9(1):7342. doi: 10.1038/s41598-019-43663-z.
The secreted mucilage trails of the diatom Navicula sp. in the process of motility were studied by scanning electron microscopy (SEM), transmission electron microscope (TEM), atomic force microscopy (AFM) and Raman spectra etc. Contrary to previous studies, force measurement was taken directly on the mucilage trails of live cells using the method of in situ force mapping by AFM. The retraction force curve presented an increased tip-substrate peak and a small saw-tooth pattern tip-mucilage peak. Especially, same measurements on various substrates with different surface energy revealed that the mucilage trails actually functioned as a medium increasing the adhesive force between the diatom and substrates, which is crucial to diatom's adhesion and locomotion. In addition, the mechanical properties of mucilage trails were quite different from mucilage strands in the maximum adhesive force and the maximum polymer extension length. Raman spectra indicated the difference in compositions that both of the two kinds of mucilages had proteins and polysaccharide, but the mucilage strands contained some other components with C=O, -CH- and -CH asymmetric and symmetric stretches. This research hammers out more precise information about mucilage trails which would be useful in terms of diatom motility and biofouling prevention.
利用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、原子力显微镜（AFM）和拉曼光谱等方法研究了硅藻 Navicula sp. 在运动过程中分泌的粘性轨迹。与之前的研究不同，我们直接使用原子力显微镜（AFM）的原位力映射方法对活细胞的粘性轨迹进行了力测量。回缩力曲线呈现出增加的尖端-基底峰和小锯齿形的尖端-粘液峰。特别是，在具有不同表面能的各种基底上进行相同的测量表明，粘液轨迹实际上起到了增加硅藻和基底之间附着力的介质的作用，这对硅藻的附着和运动至关重要。此外，粘液轨迹的机械性能在最大附着力和最大聚合物延伸长度方面与粘液丝有很大的不同。拉曼光谱表明，这两种粘液都含有蛋白质和多糖，但粘液丝含有其他一些含有 C=O、-CH-和-CH 不对称和对称伸展的成分。这项研究提供了关于粘液轨迹的更精确信息，这对于硅藻的运动和生物污染预防是有用的。
